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AP in humans is characterized by significant reduction of peripheral blood T- and B-lymphocytes.

Cholecystokinin (CCK) acting through its G protein-coupled receptor is now known to activate a variety of intracellular signaling mechanisms and thereby regulate a complex array of cellular functions in pancreatic acinar cells. The best studied mechanism is the coupling through heterotrimeric G proteins of the G q family to activate a phospholipase C leading to an increase in inositol trisphosphate and release of intracellular Ca 2π . This pathway along with protein kinase C activation in response to the increase in diacylglycerol stimulates the secretion of digestive enzymes by the process of exocytosis. CCK also activates signaling pathways in acini more related to other processes. The three mitogen activated protein kinase cascades leading to ERKs, JNKs and p38 MAPK are all activated by CCK. CCK activates the ERK cascade by PKC activation of Raf which in turn activates MEK and ERKs. JNKs are activated by a distinct mechanism whish requires higher concentrations of CCK. Both ERKs and JNKs are presumed to regulate gene expression. CCK activation of p38 MAPK also plays a role in regulating the actin cytoskeleton through phosphorylation of the small heat shock protein HSP27. The PI3K-PKB-mTOR pathway is activated by CCK and plays a major role in regulating protein synthesis at the translational level. This includes both activation of p70 S6K leading to phosphorylation of ribosomal protein S6 and the phosphorylation of the binding protein for initiation factor 4E leading to formation of the mRNA cap binding complex. Other signaling pathways activated by CCK receptors include NF-kB and a variety of tyrosine kinases. Further work is needed to understand how CCK receptors activate most of the above pathways and to better understand the biological events regulated by these diverse signaling pathways.

Gastrointestinal perforations, leaks and fistulas may be serious and life-threatening. The increasing number of endoscopic procedures with a high risk of perforation and the increasing incidence of leakage associated with bariatric operations call for a minimally invasive treatment for these complications. The therapeutic approach can vary greatly depending on the size, location, and timing of gastrointestinal wall defect recognition. Some asymptomatic patients can be treated conservatively, while patients with septic symptoms or cardio-pulmonary insufficiency may require intensive care and urgent surgical treatment. However, most gastrointestinal wall defects can be satisfactorily treated by endoscopy. Although the initial endoscopic closure rates of chronic fistulas is very high, the long-term results of these treatments remain a clinical problem. The efficacy of endoscopic therapy depends on several factors and the best mode of treatment will depend on a precise localization of the site, the extent of the leak and the endoscopic appearance of the lesion. Many endoscopic tools for effective closure of gastrointestinal wall defects are currently available. In this review, we summarized the basic principles of the management of acute iatrogenic perforations, as well as of postoperative leaks and chronic fistulas of the gastrointestinal tract. We also described the effectiveness of various endoscopic methods based on current research and our experience.

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Background Endoscopic techniques have become the first-line therapy in bariatric surgery-related complications such as leaks and fistulas. We performed a systematic review and meta-analysis on the effectiveness of self-expandable stents, clipping, and tissue sealants in closing of post-bariatric surgery leak/fistula. Methods A systematic literature search of the Medline/Scopus databases was performed to identify full-text articles published up to February 2019 on the use of self-expandable stents, clipping, or tissue sealants as primary endoscopic strategies used for leak/fistula closure. Meta-analysis of studies reporting stents was performed with the PRISMA guidelines. Results Data concerning the efficacy of self-expanding stents in the treatment of leaks/fistulas after bariatric surgery were extracted from 40 studies (493 patients). The overall proportion of successful leak/fistula closure was 92% (95% CI, 90-95%). The overall proportion of stent migration was 23% (95% CI, 19-28%). Seventeen papers (98 patients) reported the use of clipping: the over-the-scope clips (OTSC) system was used in 85 patients with a successful closure rate of 67.1% and a few complications (migration, stenosis, tear). The successful fistula/leak closure using other than OTSC types was achieved in 69.2% of patients. In 10 case series (63 patients), fibrin glue alone was used with a 92.8-100% success rate of fistula closure that usually required repeated sessions at scheduled intervals. The complications of fibrin glue applications were reported in only one study and included pain and fever in 12.5% of patients. Conclusions Endoscopic techniques are effective for management of post-bariatric leaks and fistulas in properly selected patients.